You want to loose belly fat in 1 month?

Short of Liposuction, there's no way to target where to lose fat. You have to try the old fashoined approach of eating less/healthier and exercising more to lose some fat all over. Try to do something that'll get your heart rate up for one hour each day.

And only dieting during dinner is unlikely to make enough of a difference to make you lose weight. You have to watch your diet for every meal.

A good place to start is to stay away from all sodas and everything deep fried. Stuff that's glazed or sugar coated isn't a good idea either. Chocolates will have to go too.

And don't expect too much change over one month. The healthy plan is to try to lose weight at a similar rate as you out it on. For a month anything between 4-8 lbs would be an OK result